Notes on the ecology of Thaumatomyrmex spp. (Hymenoptera : Formicidae : Ponerinae) in southeast Bahia, Brazil

We report here basic ecological information on three species of ants belong ing to the rarely collected Thaumatomyrmex genus, namely T. atrox Weber, T. contumax Kempf and T. mutilatus Mayr. These species were studied on cocoa plantations and in forest remnants in southeast Bahia, Brazil. The apparent rarity of Thaumatomyrmex spp., and especially of T. atrox, appears to stem from inadequate sampling methods. Our results indicate that the use of the Winkler sack method is exceptionally efficient in collecting these litter cryptic ants, Our observations suggest that many ecological characteristics of Thaumatomyrmex spp. (rain forest habitat, variable nest density, and sm all colony size) are a direct adaptive response to the pressures imposed by their specialized predator behavior of Polyxenidae millipedes. Furthermore , we postulate that these species are characterized by sporadic and continu ous production of males and by a monogynous queenless structure, as describ ed in other Ponerinae ants.